Draw shadow only from 3 sides of UIView

Question

I\'ve successfully implemented drawing a shadow around my UIView like this:

block1.layer.masksToBounds = NO;
block1.layer.shadowOffset = CGSizeM         


        

Answer 1

A bit of improvement for other answers, thanks to Ashok R for swift code.

Since we were creating a triangular view in the background of the view with shadow on all sides, and a white triangle on the sides shadow is not needed.

It breaks in case of views with width comparatively larger than height.

A workaround will be to shift the path for the line where shadow is not needed a bit towards that side of view, instead of creating the triangular view Path completely.

I have created an extension for that -

extension UIView {
    func addshadow(top: Bool,
                   left: Bool,
                   bottom: Bool,
                   right: Bool,
                   shadowRadius: CGFloat = 2.0) {

        self.layer.masksToBounds = false
        self.layer.shadowOffset = CGSize(width: 0.0, height: 0.0)
        self.layer.shadowRadius = shadowRadius
        self.layer.shadowOpacity = 1.0

        let path = UIBezierPath()
        var x: CGFloat = 0
        var y: CGFloat = 0
        var viewWidth = self.frame.width
        var viewHeight = self.frame.height

        // here x, y, viewWidth, and viewHeight can be changed in
        // order to play around with the shadow paths.
        if (!top) {
            y+=(shadowRadius+1)
        }
        if (!bottom) {
            viewHeight-=(shadowRadius+1)
        }
        if (!left) {
            x+=(shadowRadius+1)
        }
        if (!right) {
            viewWidth-=(shadowRadius+1)
        }
        // selecting top most point
        path.move(to: CGPoint(x: x, y: y))
        // Move to the Bottom Left Corner, this will cover left edges
        /*
         |☐
         */
        path.addLine(to: CGPoint(x: x, y: viewHeight))
        // Move to the Bottom Right Corner, this will cover bottom edge
        /*
         ☐
         -
         */
        path.addLine(to: CGPoint(x: viewWidth, y: viewHeight))
        // Move to the Top Right Corner, this will cover right edge
        /*
         ☐|
         */
        path.addLine(to: CGPoint(x: viewWidth, y: y))
        // Move back to the initial point, this will cover the top edge
        /*
         _
         ☐
         */        
        path.close()
        self.layer.shadowPath = path.cgPath
    }

and set the boolean true for whichever side you want the shadow to appear

myView.addshadow(top: false, left: true, bottom: true, right: true, shadowRadius: 2.0)

// shadow radius is optional above and is set as default at 2.0

or myView.addshadow(top: true, left: true, bottom: true, right: true, shadowRadius: 2.0)

or myView.addshadow(top: false, left: false, bottom: true, right: true, shadowRadius: 2.0)